Propeller hub



J. A. ROCHE PROPELLER HUB Filed July 29. 1940 3 Jan. 4, 1944.

4 Sheets-Sheet l //V VENTOR JEAN A ROCHE Jan. 4, 1944. J ROCHE 2,338,302

' PROPELLER HUB Filed July 29, L940 4 Sheets-Sheet 2 Afro/M57 J. A. ROCHE PROPELLER HUB Filedjaul sze. 1940 Jan. 4, 1944.

4 Sheets-Sheet 3 A TTO KNEY Jan. 4, 1944. J A. ROCHE 'PROPELLER HUB Filed July 29 1940 4 Sheets-Sheet 4 ATTORNEY Patented Jan. 4, 1944 UNITED STATES PATENT OFFICE 2,338,302 PROPELLER HUB Jean A. Roch, Dayton, Ohio Application July 29, 1940, Serial No. 348,139

20 Claims. (Cl. 170-173) This invention relates to a hub for a propeller, such as is used on aircraft and for like purposes. One object of the invention is to provide such a hub having simple compact means for effecting an efliclent yieldable driving connection between the blades and the driving shaft.

A further object of the invention is to provide such a yieldable connection which will be applicable to continuous blade structures in which an intermediate part of the blade structure constitutes the driven member of the hub.

A further object of the invention mt provide -ment with relation thereto about an axis passing through the centerof gravity of the propeller and substantially normal to the plane formed by the line connecting the tips of the two blades and the axis of rotation, that being the axis about which motion of the propeller will not'result in a change such a hub in which the driven member will be free to tilt against yieldable resistance and thuspermit the blades to rotate out of a track when their thrust isunequal.

A further object of the positive means for centerin! the driven member 1 of the hub with relationto the driving member thereof and maintaining same so centeredjduring the tilting of the driven member.

A further object of the invention is toprovideinvention is to provide blades I I.

such a hub for a wooden propeller with means for preventing the splitting of the wood. A further object of, the invention is to provide such a hub which is applic'ahle to- 'aflanged 'propeiler-shaft.

Othe objects of as the ub is described in detail. a I {I In the accompanying drawings Fig.1;isia front elevation, partly in section, withf 'thef' blades broken away, showing oneembodlmen't'of my the invention'may "appear of pitch of. either blade. Yieldable means are provided to establish a driving connection between the driving member and the driven memher and to lightly resist the above-described limited tilting movement of the propeller with rela- 7 'tion to the driving member.

In the embodiments shown in Figs. 1 to 4 the driven member 10 of the hub is .a part ofa continuous blade structure and is integral-with the I The driven member, whether inte- .gral with or formed separately from the blades, is' provided'with an opening or slot I: to recelve the driving member IS on which the driven member is supported for both a limited rotatary movement and a tilting movement. The driving member is provided with parts arranged in opposed relation to and spaced from the adjacent walls of the opening in the driven member to; receive the resilient means which cushions thev invention; Fig. 2 is a side elevation, partiy in section, of the hub of Fig. 1; Fig. 3 is a.-front ele- 1 vation, partly in section, of another embodiment of my invention, with the blades broken-. away-;' Fig. 4 is a longitudinal sectional view .takenbn the line 4-4 of Fig. 3 and partly broken away; a Fig. 5 is a partial section oi .ahub, showlng' a modified form orbearingzfFig; -6- is -..a '-simil ar driven member and, resists the tilting thereof. ,Prei'erably theopening I2 is an elongate openin'g, or relativelywide' slot, extending entirely through the driven member of the hub and having its'jmajor dimension lengthwise of the blades,

ithe sid'e-wafls of the opening being substantially parallel.- The driving member of the hub comprises a tubular central portion i4 having a view showing anotherformof barin Fig. l is I a plan view of a modiflediomi of hub with'thepropeller blades broken away; F 8 is a front elevation of the hub .offFig. .7; and Fig. 9 is a sectional view. taken on-theline 9-9'oi' Fig. 8.

In the'se drawings Irhave illustrated certain embodiments of my invention, each of which is designed primarily foracontinuous bla'destructure in which the driven member of the hub is an integral part of theblade structure, such as the usual one piece wooden propeller. It will be understood, however, .that these embodiments are shown for the purpose of illustration only and that the invention may take various forms and may be applied to propellers in various ways.

tapered longitudinal bore to receive the tapered end of the driving shaft 15, which may be rigidly secured thereto in any suitable manner, as by a .key l6 ands. nut II. This tubular portion of the driving member is of a diameter approximately equal to the width of the opening i2 and it is provided on opposite sides with vanes l8 which extendtherefrom in the direction of the respective blades and are spaced from the respective sides of the opening. In the present instance, the lateral surfaces of the vanes l8 converge toward the respective ends of the opening it and are provided. with openings I9 to reduce the weight thereof. The fore and aft faces or edges of each vane converge slightly toward the adjacent end of the opening l2, as shown at 22, and

the radial outer faces or edges are so shaped as to permit tilting of the propeller about the axis defined above. as shown at 20. Thus clearance spaces are provided between the outer faces and the fore and aft faces of the vanes with respect to the slot or opening in the driven member to permit the tilting movements of the blades. The high points of the end edges of the vanes'are located close to the curved end walls of the opening but when the driven member is formed of wood this high point does not contact therewith. Yieldable elements 23, such as rubber having the desired degree ofresiliency. are interposed between the sides of the vanes and the aiflacent side walls of the opening and are preferably confined therebetween under pressure, so that they tend to hold the driven member normally in a predetermined position with relation to the driving member. Preferably they are initially of such a length that they project slightly beyond the spaces between the vanes and the walls of the opening and these projecting portions are then pressed into-the spaces to cause the rubber to be confined under pressure. Annular end plates 24 are rigidly secured to the driven member. as by bolts 25, and extend across the edges of the vanes and the ends'of the rubber blocks to retain the latter in the respective spaces and to hold the driven member against axial movement with relation to the driving member, and these plates contact the projecting ends -of the rubber blocks during the assembly of the hub and, when the bolts are tightened down, press these projecting portions of the blocks into and retain them inthe respective recesses. In the present arrangement the frictional contact between the rubber inserts and the vanes provides a light but sufficient resistance to the tilting of the blades, and, if desired. the rubber elements may be treated with talc or the like to facilitate tilting and to aid in the insertion of the rubber elements. If desired, the clearance spaces at the edges of the vanes may be filled with soft rubber, as shown in the drawings, but this is not essential and in some cases it may be preferable to leave the spaces open.

Means are provided for positively centering the driven member with relation to the driving member and for maintaining the driven member so centered during its tilting movement. This centering means may take various forms but it preferably comprises bearings arranged at the respective ends of the hub and of such a character as to permit both the rotatory movement and the tilting movement of the driven member. As shown in Fig. 2, the driving member i3 is provided near each end thereof with an annular bearing surface 25 concentric with the aids of the hub, and the inner edge of each annular end plate is provided with a bearing surface 21 which cooperates with the bearing surface 26 to center the driven member with relation thereto. In the arrangement shown in this figure the two bearing surfaces contact directly one with the other and are so shaped as to permit the tilting movement of the driven member as well as its rotatorv movement. In this arrangement the two hearing surfaces at both ends of the hub conform substantially to portions of a sphere the center of which is coincident with the center of mass of the propeller, thus permitting the driven member not only to have rotatory movement about the axis of the hub but also to tilt about an axis such that the pitch of the blades will not be varied by such tilt.

. 23 which extends from the opening lengthwise assaaoa In a hub of this character, when used with a wooden propeller, the impulses of the vanes, even when cushioned, may have a tendency to split the driven member of the hub, this being particularly true if the bolts do not fit tightly in their holes. I have therefore provided .the hub with means for preventing the splitting of the driven member. As shown in Figs. 1 and 2 the driven member-is provided at'each end of the opening I! with a relatively short preformed slot of theblade. By so slotting the drivenmember the lateral portions thereof are provided with resiliency suiiicient to enable the same to be pressedinto firm contact with the bolts with little or no tendency to split the wood.-

In Figs. 3 and 4 there is illustrated a different means for preventing the splitting of the hub. As shown in those figures the driving and driven members are substantially similar to those shown in Figs. 1 and 2 butthe'end plates 29 are provided with parts which extend for a substantial distance beyond the opening l2 of the driven .member, they being here shown as having their ends tapered, at 30, and the bolts 3i which connect the plates with the driven member extend through these projecting portions of the end plates. Other bolts 32 extend through the driven member transversely to the bolts 3i and adjacent the respective ends of the opening II. By spacing the bolts 3i a substantial distance from the ends of the opening the bolts 32 maybe inserted between the bolts 3! and the opening so as to place them at the point of greatest strain. R6131. tlvely thick washers 33 are placed about the respective ends of the bolts 32 to provide the latter with relatively large surfaces to contact the 'driven membe .The bolts 32 are so tightened as to resist any tendency of the hub to split, while the function of the bolts 3i is merely to secure the end plates to the hub so as to close the opening or slot, retain the rubber inserts therein and maintain the outer bearing members in proper relation to the propeller and in true spherical relation to each other.

In Fig. 4 there is also shown another type of bearing for centering the driven member with relation to the driving member. As there shown, there is secured to the driving member near each end thereof an annular bearing member 34 the bearing surface of which is in the form of a ball race in which are mounted balls 35. The driven member is provided at each end with a bearing surface 35 which contacts with the balls 35 and these bearing members are shown as conforming substantially to portions of a sphere the obnter of which is coincident with the center of mass of the propeller. In the construction shown in Fig. 4 the bearing surfaces 36 are formed on a annular bearing members 31 which are mounted in recesses 38 in the inner portions of the end plates 29.

In Figs. 5 and 6 there are shown'ot'her forms of bearings. The bearing of Fig. 5 is'similar to that shown in Fig. 2 with the exception that the inner edge of each end plate is flared, as shown at 39, to provide a space in which there is mounted an annular member .40. of suitable bearing material, on which is formed a bearing surface 4| which contacts with a bearing surface 42 on the driving member, the latter being provided with a lubricant groove 43 in which there may, if desired, be inserted an absorbent element or wick impregnated with lubricant. The bearing surfaces 4| and 42 have direct contact one with the other and are or partial Spherical form as described in connection with Fig. 2.

In Fig. 6 the driving member is provided-"with an annular'bearingrmembe'r 44 having its-outer bearing member 46 that it may have. such-movement with relation thereto. For this purposethe bearing member 46 is provided on its outer face.

with a bearing surface 49 which cooperates with a bearing surfaceSO formed on the inner face of the outwardly flared-portion ii of theend' with a lubricant groove "52..

plate, and provided the bearing surfaces 49 and 50 being of spherical form as above described and thereby permitting driving member. Thisis a desirable'construction because it provides a rolling type of. bearing for the motion' due to torque impulses which occur continuously as long as the engine isrunningand, therefore, might produce heat and galling inc-a friction type of bearing, awhile a simple plain spherical bearin .In-Figs. '7; Sand 9, thereis is shown .to take care-:of :the tilting action which -.occurs relatively. 2 seldom. that isonly whens. change in blade-thrustoccurs shown-an-embodiment of the. invention designed for-.use -wi'thra flangeddriving. shaft,'that is,- the shaft doesnot extend through either member of the-'hubj but' is provided with means whereby it may.be\secured to the driving member. In these figures-thereiis shown a portion of a driving shaitjt'provided at .its end with -a circumferential flange 1-54.

Rigidly secured to this flange is .a housing which constitutes the driving member of the'hub.

This housing may take various forms and, .as here shown, it comprises a plate 56 rigidly'secured to the flange 54. as by screws 51. Rigidly-secured to the plate 56 is a u-shaped member comprising side walls 58-anda bottom wall 69. .ThisU- shaped member is rigidly secured at its open end as here shown, is provided with apertured lugs 60 to receive the bolts 8| which connect the same with the plate; An intermediate portion 62 of a blade structure is mounted between the-side walls 58 of the housing with its lateral edges spaced from the respective side walls, and yieldable elements such as blocks to the plate 56 and.

63 of resilient rubber are inserted between the I lateral surfaces of the blade structure and the respective side walls. Preferably these rubber blocks extend beyond the front and rear surfaces of the blade structure 52 for contact with the end wall 59 and plate 56. Thus these resilient elements provide a yieldable driving connection between the driving member of the hub. and". the blade structure and permit the blade-structure to tilt with relation to the driving member about an axis passing through the center of gravity of the. propeller and normal to the plane established by the axis of rotation and a line connect.- ing the blade tips. In the present instance the side walls 58 of the housing are substantially parallel and the lateral surfaces of the blade structure 82 are substantially parallel one with the driven member to tilt with relation-to the bearing 'membersa;65 and? I the other and withathe'sidewalls. thus permitting the-use -of. a: rubber-izblocka or ubstantially uniform; thickness throughoutiitsi area.

'.-'I'he:means;iorrcenteringathezblade.structure or *driven mcmbenwithrrclationr.-to=:the:driving.mem ber "on" housingsares-substantially-2 simllartto the centering-meansiabovedescribedzhut-diifer slight-- in axial .aIinementwithtfthe -.opening rekzand :ein

am annular ball. race this ropeningziiszt mounted erblade: structure-r is iit to;receiveixballssflas.

.providedq-ombothrit'smear anderfront. sides" withbearing :memberstwhiclrgcooperate -With the" re.- -spective bearingemembersi thefll'iving'member and are shapedxtoi tilting movement. of :the blade-structure: tin --thej. particular construction shown-t the kbeariiigasnembers -{or the blade structure are: in di ram. oi plates .58 and 0 rota. .diametengreaten thang the diameter. of the =sos;that-' the: surface of eaehabearingepl y ,ng age the oi theerespectivebalL -races. The; bearing surfaces .ota'these' plates: conform i' 1bstantially to. of: ;hem;.- the-.center whiehiacoincident' with ithecentereofrmassr bin-propeller. ordento retain.;the .bearing-r:niembersf=69;.ahd -10 iniflxed relativerpositions-theware;preferably. i-igid1y, connected "one" withither-other. raesrhereishown. a shank)! iris rigidly. ure'd tmgor. 'formed integral with, the .plate -i i sc entendstthrough the .blade .structuregandgprovidedt neaifiits forward: endwith a: reducedeportioir ,forms thereon. a shoulder 1.1.2.. IZ'Ihe-ifmntbcaring '.plate .10 .is mounted .onathiszreducedJ-portirin .of the shank clamped .-.-.aga'.inst ..the shoulder 12 .by a

driving .memberseshowninil-igs. "7,".8 and i 9, care the reverse oi.those;-shown-.in'zthe other figures;

v the .drivenfmemberris-xcapable. of? both: rotatory movement anditiltipgamovementiwith.relation to the drivingrmember,;.zazidiin common withthe other embodiments or the invention this form of hub permits thezpropellerr to untrack. and permits torsional displacement of the driving shaft with respect to Jthepropeller and at the same time provides positive metal to metal centering means for the :ldrive'n member.

I While I havesshownandldescribed certain embodimentsoi' myinvention I wish it to be understood that I I do "not-'desire tobe limited .to 1 the details' thereof i'asnvarious .modiflcations may occur toia' person skilled .inr-theart.

Having now fully descrlbedmy invention, what I claim as new and 'desiretoxsecure by Letters Patent-is:

1.. In. a propellerz'ihub; adriving member having means'ior: securing the same to a drivin shaft, a'rblade supportingrdriven'member, one of said membershaving an opening inwhich' the other member .isxso"mounted that said driven member may have tilting-movement to .permit untraclring without .permitting pitch changes. in the blades; said opening" having substantially parallel side walls'andzthe member which is mounted in said opening having parts opposed to and spaced from --said' side walls, resilient elements mounted between said side walls and said opposed. parts to drivingly connect said driving and driven members and' to i lightly resist'the untracking movement oi said driven member, said members having cooperating bearing surfaces to center said driven member with relation to said driving member, at least one or said bearing surfaces being transversely curved about an axis located substantially at the center or the mass orthepropeller to permit said driven member to tilt with relation to saiddriving member.

2. In a propeller hub, a driving member having means for securing the same to a drivin shaft, a blade supporting driven member, one of said members having an opening in'which the other member is so mounted :that said driven member *may have tilting movement to permit untracking without permitting pitch changes in the blades, said opening having substantially parallel side walls and the member which is mounted in said opening having parts opposed to and spaced from said side walls, resilient elements 'mounted between said side walls and said opposed parts to drivingly connect said driving and driven members and to lightly resist the untracking movement-of said driven member, said driving memberhaving near each end thereof a ball race, concentric with the axis thereof, balls mountedin said race, and said driven member having bearing surfaces engaging theballs in the res ective races to"centerfsaiddriveh member with relation tosai d driving memberfeach' 01' said bearing surfaces being curved about an axis I located substantially at the center of mas of the propeller'to" permit the tilting movement of Said drivenmember. 3. In a propeller hub, a driving member having means; tor"securing the'same to a driving 'shaftfa blade supporting member, one of said members having'anopeningin which the other member is so mounted that said driven member mayhave tilting movement to permit untracking without permitting pitch changes in the blades, the member which is mounted in said opening having parts spaced about its axis of rotation'and arranged in opposed relation to and spaced from adjacent parts of the other member, resilient elements mounted between said opposed parts to d rivingly connect said members and to lightly-resist the untracking movement of said driven member, said members having cooperatingbearing surfaces to center said driven member with relation to said driving member, at least one of said bearing surfaces being transversely curved about an axis located substantially at the center of mass of the propeller, to permit said driven member to tilt with relation to said driving member.

4. In a propeller hub, a driving member, a driven member having an elongate opening to receive said driving member and mounted about said driving member for tilting movement with relation thereto, said driving member having oppositely extending parts arranged between and spaced from the side walls of said opening, resilient elements interposed between the respective sides of each of said parts and the adjacent walls of said opening, said driving and driven members having cooperating bearing surfaces concentric with the axis of said hub to center said driven member with relation to said driving member, at least one of said bearing surfaces being transversely curved about an axis located substantially at the center Of mass otthe propeller to permit the tilting movement of said driven member.

5. In a propeller hub, a driving member, a driven member having an elongate opening to receive said driving member and mounted about said driving member i'or tilting movement with relation thereto, said driving member having oppositely. extending parts arranged between and spaced from the sidewalls or said opening, resilientelement interposed between the respective sides of each of said parts and the adiacent'walls of said opening, said drivingm'ember having near each end thereof a bearing surface concentric with its axis, and 'end plates extending across the respective ends or said opening, rigidly secured to said' driven member and each having a bearingsurface to cooperate with the adjacent bearing surface of said driving member, at least one of said bearing surfaces of each pair being said walls to provide a yieldable driving connec' tion between said driving member. and said driven member. endplates extending across the respective ends of said opening, bolts for securing said end plates to said blade-structure and other bolts extending through said blade structure adjacent,

the respective sides of said opening and trans- 'vers'ely to the first mentioned bolts.

'1. In a propeller hub, a continuous blade structure having an intermediate-portion provided with an opening and constituting the driven member of" a two part hub, a driving hub mem-v posed between said parts 01. said driving member and said walls to provide a. yieldable driving connection between said driving member and said driven member, endplates extending across the respective ends of said opening and having parts projecting beyond the sides of said opening toward'the respective blades, bolts connecting said projecting parts or the two end plates one with the other and with said blade structure, and other bolts extending through said blade structure adjacent said sides of said opening and transversely to the first mentioned bolts.

8. In a propeller hub, a driving member, a driven memben mounted for limited rotatory movement with relation to said driving member about the axis-of the latter and for tilting movement with relation 'tosaid' driving member to permit untraclgin'gf, without permitting pitch changes inthe bladesieach member having parts arranged about said axisinopposed relation to the adjacent parts oftbe other member, resilient means interposed betweenthe respective opposed parts or said members to drivingly connect the same and to resist the tilting movement of said driven member, said driving and driven members having near each end thereof a pair of cooperating annular bearing surfaces, at least one bearing surface of each pair being curved about the center of mass of said propeller to permit the tilting movement of said driven member.

9. In a propeller hub, a driving member, a driven member mounted for limited rotatory movement with relation to said driving member ment with relation to about the axis of the latter and for tilting movesaid driving member to permit untracking without permitting pitch changes in the blades, each member having parts arranged about said the adjacent parts of the other member, resilient means interposed between the respective opposed parts of said members to drivingly connect the same and to resist the tilting movement of said driven member, said driving member having near each end thereof a part provided with a bearing surface concentric with the axis of said hub and said driven member having parts provided with bearing surfaces to cooperate with the respective bearing surfaces of said driving member, the

ing substantially to portions ofa sphere the center of which is coincident with the center of mass of the propeller. v

10. In a propeller hub, a driving member, a driven member mounted for limited rotatory movement with relation to said driving member about the axis of the latter and for tilting movement with relation to said driving member to permit untracking without permitting pitch changes in the blades, each member having parts arranged about said axis in jacent parts of the other member, resilient means interposed between the respective opposed parts of said member to drivingly connect the same and to resist the tilting movementofsaid driven member, said driving member having near each end thereof a part provided with abea'ring suraxis in opposed relation to opposed relation to the ad-,

hi5 bearing surfaces of said driven member coniormraces, and means for connecting said driven member with its said bearin members for movement with relation thereto about an axis substantially coincident with the center of mass of said propeller.

bers having near each end of said hub bearing members provided with opposed ball races, balls in said races, said driven member and its bearing members having cooperating bearing surfaces conforming substantially to the portions of a sphere the center of which is coincident with the 'center ofmass'of said propeller,- whereby said driven member may tilt with relation to its said bearing members.

14. in apropeller hub adapted for connection. with a flanged driving shaft, a housing having means for securing the same to the flange of said shaft, a .blade structure having a part mounted in said housing for limited rotatory movement with relation thereto about the axis of said hub face concentric with the axis of said hub, said driven member having .secured thereto'annular members having bearing surfaces in contact with the respective'bearing surfaces of said driving member, all of said bearing surfaces 'beingtransversely curved about an axis located substantially at the centerof the mass of said propeller.

11. In a propeller hub, a driving member, a driven member mounted for limited rotatory movement with relation to said driving member about the axis of the latter and for tilting movement with relation to said driving member to permit untracking without permitting pitch changes in the blades, each member having parts arranged about said axis in opposed relation to the adjacent parts of the other member, resilient means interposed between the respective opposed parts of said members to drivingly connect the same and to resist the tilting movement of said driven part 0! 88.1(1 blade structure having 155 lateral and for tilting movement with relation to said housing in a plane passing through aid axis, said surfaces spaced fromthe adjacent walls of said housing, resilienteelenients. interposed between said lateral surfaces and said adjacent walls to drivingly connect said driving member with said blade structure and to resist the tilting movement of said blade structure, and means to posi- V tively center said blade structure against radial member, said driving member having a ball race concentric with the axis of said hub near each end of the latter, balls in said races, and said driven member having annular bearing surfaces engaging the balls in the respective races, each of said bearing surfaces being transversely curved about an axis located substantially at the center of mass of said propeller,

12. In a propeller hub, a driving member, a

driven member mounted for limited rotatory movement'with relation to said driving member about the axis of the latter and for tilting movement with relation to said driving member to permit untracking without permitting pitch changes in the blade, each member having parts arranged about said axis in opposed relation to the adjacent parts of the other membeigvresilient means interposed between the respective opposed parts of said members to drivingly connect the same and to resist the tilting movement of said driven member, said driving and driven members having near each end of said hub bearing members provided with opposed ball races, balls in said displacement with relation to said housing.

15. In a propeller hub adapted for connection with a flanged driving shaft, a housing having means for securing the same to the flange of said shaft, 9. blad structure. having a part mounted in said housing for limited rotatory movement with relation thereto about the axis of said hub and for tilting movement with relation to said housing in a plane passing through said axis, said part of said blade structure having its lateral surfaces spaced from the adjacent walls of said housing, resilient elements interposed between said lateral surfaces and said adjacent walls to drivingly connect said driving member with said blade structure and to resist the tilting movement of said blade structure, and bearings interposed between said housing and said part of said blade structureto center the latter with relation to said housing and to support said blade structure for tilting movement with relation to said housing.

16. In a propeller hub adapted for connection with a flanged driving shaft. 2. housing having means for securing the same to the flange of said shaft, a blade structure having a part mounted in said housing for limited rotatory movement with relation thereto about the axis of said hub and for tilting movement with relation to said housing in a plane passing through said axis, said part of said blade structure having its lateral surfaces spaced from the adjacent walls of said housing, resilient elements interposed between saidlateral surfaces and said adiacent walls to drivingly connectsaid driving member with said.

blade structure and to resist the tilting movement of said blade structure, said housing having near each end thereof a bearing member concentric with its axis, and said blade structure having bearing members to cooperate with the respective bearing members of said housing, at

and for tilting movement with relation to said housing in a plane passing through said axis, said part of said blade structure having its lateral surfaces spaced from the adjacent walls of said housing, resilient elements interposed between said lateral surfaces and said adjacent walls to drivingly connect said driving member with said blade structure and to resist the tilting movement of said blade structure, said housing having near each end thereof a ball race, balls in said races, bearing members carried by said part of said bladestructure and provided with bear-1 ing surIaces to engage the balls in the respective ball races, said bearing surfaces conforming substantially to portions of a sphere the center of which is coincident with the center of mass of said propeller, and means for rigidly connecting said bearing members one to the other.

18. In a propeller hub adapted for connection with a flanged driving shaft, a housing comprising a plate having means for securing the same to the flange of said shaft, vand a substantially U-shapedmem'ber rigidly secured at its open side to said plate and having its side walls'substantially parallel, a blade structure having an intermediate part mounted between said side walls of said member for limited rotatory movement with relation thereto about the axis of said hub and for tilting movement with-relation thereto in a plane passing through said axis, resilient elements interposed between the lateral surfaces of said part of said blade structure and the adjacent side walls to drivingly connect said drivin member with said blade structure and to resist the tilting movement of the latter, and means to center said blade structure with relation to said housing and to maintain the same centered during tilting movement thereof.

19. In a propeller hub, a driving member, a driven member having an elongate opening to receive said driving member and mounted about said driving member for tilting movement with 5 relation thereto to permit untracking without permitting pitch changes in the blades, said opening having opposed 'walls on each side of the axis of said driving member, said driving member having oppositely extending vanes arranged between and spaced fromthe respective opposed walls of said opening, and resilient elements interposed between saidwvanes and the respective'walls of said opening to drivingly connect said driven member with said driving member and to lightly l5 resist the untracking movement of said driven member, said driving member and said driven member having neareach end of said hub cooperating bearing surfaces arranged about and concentric with the axis of said driving member to center said driven member with relation to said driving member, at least one of said hearing surfaces being transversely curved about an axis located substantially at the center of mass of the propeller to permit said driven member to tilt with relation to said driving member.

4 20. In a propeller hub, a driving member, a driven member having an elongate opening to receive said driving member and mounted about said driving member for tilting movement with relation thereto to permit 'untracking without permitting pitch changes v in the blades, said opening having substantially parallel walls on each side .of the axis' of said driving member, said driving member .;having oppositely extending vanes arrangedbetween and spaced from the re-- spective parallel walls of said openings and decreasing inthicknessftoward' the ends of said opening, .thus providing between said vanes and the respective." walls/spaces, which increase in 40 depth toward' the respective of said opening. and blocks ofaresilient materialarranged in and filling said spaces to drivingly connect said driving member with said driven'member and to yieldably resist theuntracking movement of the latter, said driving member and said driven member having near each end of said hub cooperating bearing surfaces arranged about and concentric with the axis of said driving member to center said driven member with relation to said driving member, at least one of said bearing surfaces being transversely curved about an axis located substantially at the center of mass of the propeller to permit said driven mfiiber'to tilt with relation to said driving member.

as JEAN A. Rocrnix. 

